1. Field of the Invention
The present invention relates to a recording tape cartridge and a drive device thereof for positioning a case accommodating a reel, upon which a recording tape such as a magnetic tape or the like is wound, in the drive device.
2. Description of the Related Art
Recording tapes such as magnetic tapes and the like are used as recording media for saving data (information) of computers and the like, for audio uses, for video uses, and the like. In order to prevent damage to a recording surface of such a recording tape, due to adherence of dust or the like to the recording surface, finger contact and the like, the recording tape is employed in a recording tape cartridge. In this recording cartridge, the recording tape is wound onto a reel and the reel is rotatably accommodated in a case formed of resin.
“Single reel cartridges”, in which a recording tape wound onto a single reel is accommodated in a case (these are principally used for back-up of information for computers and the like), two-reel cartridges, which are provided with two reels for winding and unwinding (for example, audio cassettes, video cassettes and the like), and the like are known as recording tape cartridges. Whenever information is to be recorded or replayed with one of these recording tape cartridges, the recording tape cartridge is loaded at a drive device (a recording/replaying device).
In a state in which the recording tape cartridge has been loaded into the drive device and the case has been positioned in the drive device, the recording tape is drawn out of the case. This recording tape is guided along a predetermined tape path, and is set at a position close to a recording/replaying head of the drive device. In this state, information is recorded onto the recording tape and/or information that has been recorded on the recording tape is replayed.
As a method for positioning a recording tape cartridge in a drive device, there are methods such as that disclosed in Japanese Patent Application Laid-open (JP-A) No. 11-126398. In such a method, seat portions are provided in reference holes, which are provided at two places in a lower surface of the case. Respective positioning pins of the drive device are inserted, and the recording tape cartridge is positioned in horizontal directions. Further, positioning of the recording tape cartridge in a vertical direction is implemented by the positioning pins abutting against the seat portions.
There are many cases in which the reference holes are dually used as hole portions of bosses for screws, which usually fix an upper case and a lower case which constitute the case. However, in such cases, the positions of the reference holes are constrained by the bosses (or the positions of the bosses are constrained by the reference holes). Further, when the hole portions are formed in the case, formation failures such as short shot due to unsatisfactory filling of resin, coarsening of a design surface due to movement of air bubbles during forming, and the like tend to occur.
Furthermore, when hole portions are formed in a case, portions corresponding to the hole portions are usually provided as inserts fixed to a movable-side mold, which are separate bodies from a movable-side mold body. Consequently, flash may occur at a parting portion between the inserts and the movable-side mold body. There is a risk that stripping off this flash may have an undesirable effect on functioning of the tape.
Correspondingly, there are also cases in which inserts are fixed to a fixed-side mold. In such cases, if flash occurs at a parting portion between the inserts and the fixed-side mold, this flash is at an outer side of the case. Therefore, this will not have any effect on functioning of the tape. However, the outer side of the case is a design surface. Therefore, because parting lines will appear on the design surface, this method is not usually employed.
Accordingly, when hole portions are formed in a case, there is some damage due to the provision of inserts at a movable-side mold or a fixed-side mold. On the other hand, in cases in which inserts are not provided, gas retained at a deeper region of a hole portion cannot escape. As a consequence, short shot of a boss is induced. The deeper the depth of the hole, the more remarkably this tendency is exhibited.